Water gauge illuminator



July 24, 1934. F. w. MILLER WATER GAUGE ILLUMINATOR Filed Sept. 28, 19312 Sheets-Sheet 1 July 24, 1934. F; w. MILLER v 1,967,477

WATER GAUGE ILLUMINATOR Filed Sept. 28, 1931 2 Sheets-Sheet 2 PatentedJuly 24, 1934 r- 1,967,477

- curren mm WATER GAUGE ILLUMIINATOR Frank W. Miller, Philadelphia, Pa.,assignor to Yarnall-Waring Company, Philadelphia, Pa., a a 7 corporationof Pennsylvania 7 Appl a oh' pt m er 28, 1931, Serial No. 563,49 mins.(01. 24o-2.15)"

My invention relates to an; illuminator for water i The illuminatorembodying the'present invengauges, being particularly adapted to usewith tion is believed to have its best and widest appli gauges of theflat glass type such as are frequently cation with water gauges of thefiat type in which used to indicate the water levels within high presthecolumn is open to. view. from the front, usui -sure boilers. Thesegauges present a -water ally througha slot of 'a'metal front plate ofthe column to vision from the front and to illuminagauge, and open toillumination at the back tion from the rear, usually through verticalslot through a correspondingly slotted bacl; plate. 2 openings in frontand rear metal plates of the The flat gauge 5may-include "a body 6normally gauge. a of metal having a verticalslot 7 forming side 10 Apurpose of the invention is to provide a water walls of the watercolumn, high and low connec- 651 gauge illuminator of the characterindicated tions, as from aboiler, into the top and bottom adapted toeasy and inexpensive manufacture and of the slot at.-'8 and 9respectively, heavy glass well suited to the needs of service. iplates'lO and 11 'clo'sing'the slot at front and rear A further purposeis to provide uniform illumi-.- respectively and the front and backmetal plates '15 nation upon the rear of a gauge column of the 12and 13vertically slotted in registry with the character indicated, and from alight bulb out of slot '7 of the body and bolts orscrews'; not shown,sight of the users of the gauge. clamping the plate members alltogether.

A further purpose is to locate an electric bulb It will be seen that thegauge column is open low down and'to the rear of. a gauge of the char-fto vision from the front through the slot 14 and 20 acter indicated andto uniformly reflect'light glass plate 10 and open to illumination atthe from the bulb diagonally upwardly into the rear rear through theslot 15 and the glass plate 11-, of the gauge column. a V r and thepresent invention is-directed to an illumi- A further purpose 15 toprovide an illuminator. nator for effectively'lighting up therearward'side of the character indicated witha light absorbent of thegauge column, as through the slot opening '25 interior surface except ata reflector directing the 15, and from a lightbulb'located out of sightof so light from a light bulb upon the gauge column. users of the'gauge.v A further purpose is to provi e an illuminator "The illustratedembodiment of 'the invention of the character indicated with a lightsocket includes a box 16, a light bulb 1'7,- and a light selectively oneither side of a boxportion of the reflector 18, the box su1tably ofsheet metal illuminator and with bracket connection to the having avertical opening 19 for presentation to gauge selectively from the saideither. side. 1 the gaugecolumn and preventing outward trans- A furtherpurpose is to provide an illuminator mission of light from thebulbexcept at the open.- of the character indicated with a combinedreing .19, the bulb being located near the bottom flector and door. v iof the outlet and' suitably rearwardly thereof,

ill appear. in the specificaand .the reflector being-curved to uniformly35 Further purposes w tion and in the claims. illumine the outlet 19 byreflected light from the i have elected to show one only of the manybulb; different forms of my invention, selecting hoW- The open-ing 19tothe'gauge is normally narever a form that is practical and efiicientinoperrow as compared to the length of a light bulb 40' ation and. whichwell illustrates the principles and the box '16 for thisreason suitably,includes forward" and rearwardportions-ZO and-21- re-, Figure 1 is asectional elevation of an illumispectively, the. forward portion20comprising a nator embodying apreferred form of the inv'en-,horizontallytapering approach to the opening tion, shown applied to agauge glass that isindi- 19 and the rearward portion 21 having parallel'45 cated in dot-and-dash lines as a hat glass type of vertical sides 22and 23, a forwardly and upwardly gauge but which is intended for aconventional illustration of any gauge to which the invention 18 as abottom adapted to open asadoor, being is adapted to be applied.

Figure 2 is a left side elevation of the structure suitable catch 26.50" shown in Figure 1, partly sectioned. The socket 27 holding the bulbis carried in Figure 3 is a top plan view of the structure aflangedmount 2'1 that is fastened interchangeshown in Figures 1 and 2. ablywith a removable cover 28 upon respective Like numerals refer to likeparts in all figures. sides of the box, the socketmount 27 closingDescribing in illustration and not in limitation one side opening 29while the flange 28 closes 55: and referring to the drawings:- theother. In)

involved.

ably formed of light copper sheet with the inner and brightly polished,

surface chromium plated and should have a curvature adapting its reflecting inner surface to best illumine theopening 19 to the gauge.

The interior surfaces of otherportions of the box are preferably madenon-reflecting.

As a result the illuminator is found to give wonderfully eflectiveillumination of the column throughout its length with a brightlineat themeniscus.

I The box is frequently desirably provided with one or more openingsnear'the bottomas at 33 and 34 and one or'more openings at the-top as at35 to provide air-lcirculationzand thereby prevent any undue heating ofthe box. 7 It will be evident that the light traveling diagonallyupwardly and What *forwardat the rearward orxoutsi-de .surface of theback glass plate, again -refracted,zbent somewhat upwardly, at theforward surfacev of the backv plate, totally reflected diagonallydownward and forwardiat the meniscus, refracted, bent somewhatforwardgat the rearwardsurface of the front glass plate, and bentsomewhat downward at theforward surface of the front glass plate Thephenomenof total reflection takes place at the separating surfacesof'contiguous transparent media of diiferent densities,-a ray' of lighttraveling in the denser medium (herewater) to impinge upon theseparating-surface (here the meniscus between the water and steam) Ibeing totally reflected back into the denser medium (here back into thewater) when the angle of incidence that the ray makes with'theseparating surface is too. great for the passage of the ray out of thedenser into the less dense medium.

The meniscus convexly curves downwardly and as a result, the angles ofincidence ,of the light rays that impinge upon the meniscus areprogressively variant at successive points of the curve causing the"beam totally reflected from the meniscus forwardly and downwardly towidely diverge thereby making the meniscus clearly visiblefrom below atwidelydivergent points.

large range of position,

as a brightline, light from the illuminator being this line into the eyeof the ing.

Having thus described my invention, what I claim asnew-and desire tosecure by Letters Patent is: l I

l. An illuminator including a box having a non reflecting interior andhaving a vertical the rearward side of a gaugeglassof the characterindicated, the opening being unobstructed from top to bottom, and alight within a low portion of the box directing illumination diagonallyupwardly upon the open- 2, An illuminator including a box having avertical opening to register with the rearward side i of a gauge 0f thecharacter indicated, the opening being unobstructed from top to bottom,a

ing the illumination diagonally upwardly upon the opening along thelength thereof and the box havinganinterior surface-unadapted toreflectligh't except at the reflector. r I 3. An illuminator including a boxhaving a non-reflecting interior and having a" vertical opening toregister with the rearward side of a gauge of the character indicated,the opening being unobstructedfrom topto bottom, a light within alowportion of the box'and a reflector diagonallydownwardly from thelight so as to be entirely below and immediately back of the lighigthelight and reflector directing the illumination diagonally upwardlyupon'the opening along the length thereof, and the reflector comprisingalso a door into the interior of the box. P 7

r 4. An illuminator including a box having a non-reflecting interior andhaving a vertical opening to register with the rearward side of a gaugeof the character indicated, the opening being unobstructed from top tobottom, a light within a low portion of the box and a supportingconnection to either side of a gauge.

5; In a liquid level gauge, walls confining the liquid column, havingtranslucent portions pn opposite sides of the column, a box having nonfor the bottom of the box having a reflecting surface and concave inplanes through theliquid column and. at right angles to-these planes.

FRANK w, MILLER.

